1. Field of the Invention
The present invention relates to a spacer structure of a display panel, and more particularly, to a spacer structure having anti-slip design.
2. Description of the Prior Art
A liquid crystal display (LCD) panel is mainly composed of a thin film transistor substrate (TFT substrate), a color filter substrate (CF substrate), and liquid crystal molecules filled therebetween. Spacers are disposed between the TFT substrate and the CF substrate in order to maintain a constant cell gap therebetween, so that dependable display quality can be ensured. Bead spacer, which is made of plastic material, is one type of conventional spacer structure. The bead spacers are spread randomly between the TFT substrate and the CF substrate to retain a constant cell gap. The haphazardly distributed bead spacers, however, may be located in display regions, and therefore cause incident light beams to scatter. The scattering of light beams leads to reduction of contrast ratio, whit point defect, color mura, etc., and therefore influences display quality and product yield.
To avoid the above defects of bead spacer, photo spacer made of photoresist has been commonly used recently. The pattern of photo spacers can be defined by a photolithography process because it uses photoresist as material. Accordingly, the size and location of the photo spacers can be precisely controlled. Please refer to FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a conventional photo spacer, and FIG. 2 is a top view of a conventional photo spacer. As shown in FIG. 1, the conventional photo spacer 10 is between a TFT substrate 12 and a CF substrate 14, and an overcoat layer 16 is disposed between the photo spacer 10 and the CF substrate 14. The conventional photo spacer 10 is fabricated by coating a photoresist layer on the surface of the CF substrate 14 and the overcoat layer 16, and then performing an exposure and development process upon the photoresist layer to define the pattern of the photo spacer 10. The CF substrate 14 having the photo spacer 10 formed thereon is then bonded to the TFT substrate 12 with a sealant (not shown). The photo spacer 10 and the TFT substrate 12, however, are slightly in contact with each other, but not solidly secured. When the LCD panel is pressed or squeezed by an external force, the photo spacer 10 will slip with respect to the TFT substrate 12 as shown in FIG. 2. Since the photo spacer 10 is mounted on the CF substrate 14, the slipping of the photo spacer 10 also causes the CF substrate 14 to move relative to the TFT substrate 12. This leads to an alignment deviation between the CF substrate 14 and the TFT substrate 12, thereby generating display problems such as light leakage and abnormal display.